ANALYSIS OF PHOSPHORUS COMPOUNDS BY USING 2D(1H 31P)–NUCLEAR MAGNETIC RESONANCE (NMR) SPECTROSCOPY IN AN OLIGOTROPHIC ENVIRONMENT.

In the current study, we developed a technique to analyze P compounds in suspended particles in an oligotrophic environment. We analyzed them using 2D 1H-31P nuclear magnetic resonance (NMR) spectroscopy. Recently, significant amount of phosphonates compounds, having C-P bond, has been suggested. Furthermore, methane emission from phosphonates are also considered under a strongly P-limited environment (e.g., methylphosphonic acid). The purpose of the current study is to detect several P compounds in an oligotrophic environment. Lake Saiko is an ultraoligotrophic lake, located on the Yamanashi Prefecture in Japan. We used a cartridge filter for collecting the suspended particles efficiently; we filtered through approximately 274 L to collect the sufficient amount of the samples during 130 minutes. The extraction was conducted for 1 hr under water temperature of approximately 60 ˚C and then, P compounds were analyzed by 1H-31P heteronuclear multiple bond correlation (HMBC) spectra. We found that among phosphonates, 2-aminoethylphosphonic acid is included in the suspended particles in Lake Saiko. This compound could also be bioavailable after orthophosphate becomes depleted conditions. The other compounds are nucleotides, such as DNA-P and RNA-P. The use of cartridge filter is useful to collect suspended particles efficiently in the oligotrophic environment, and this method can also be applicable to ocean samples because the P concentration in Lake Saiko is similar to that in ocean.